A KiwiRail train has derailed in Hamilton this afternoon.
The Northbound freight train came off its tracks under the Massey St overbridge in Frankton around 2pm.
A male driver was the only passenger and was uninjured, said KiwiRail public affairs manager Jenni Austin.
The east and north rail lines are closed, but Austin said no other trains are currently affected.
''There are no other trains held up at this stage, so I would not say the network was paralysed at all,'' Austin said.
She could not give an estimation on how long it would take to clear and reopen the track.
''Six wagons have had their wheels come off the tracks, and in one case two containers have tipped off one of the wagons and are on the ground.''
She said it was too early to know what caused the derailment.
''Our first priority is to get the train out of the way. What happens is we get cranes in to lift the wagons.
She said KiwiRail was yet to assess what track damage there might be.
''At this stage it doesn't look like there's any wagon damage.''
Two years ago a KiwiRail train derailed in almost exactly the same spot when two wagons jumped off the track at the rail junction.
KiwiRail launched an investigation into the incident, which paralysed the upper North Island rail network.
The incident closed the main north and east coast rail lines, meaning passengers expecting to board the Northern Explorer in Auckland had to be bussed to Wellington.
Ten freight services were affected by the incident.
Austin would not comment on the 2012 incident today.
In August 2012, KiwiRail was urged to carry out urgent repairs to three rail crossings in the Waikato, including one in Ruffell Rd in Te Rapa, amid claims decaying sleepers could trigger a derailment.
At the time, NZ First MP Brendan Horan claimed decaying wooden sleepers at three Waikato crossings posed a serious safety risk to rail workers and the public.
The rail crossings in question were at Kainui Rd, near Taupiri, Huntly's East Mine Rd and Ruffell Rd near Hamilton.
In 2012, KiwiRail confirmed 7000 of its imported wooden sleepers were defective and need replacing.
About 55 decaying sleepers were identified in the Waikato.
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